What is osteoarthritis and what does it do?Osteoarthritis -- known among physicians as OA -- is a disease in which cartilage breaks down. Cartilage is the spongy tissue that coats the ends of bones in joints. It acts as a shock absorber. Normally, damaged cartilage is constantly being repaired as old cartilage is degraded. When the balance between degradation and repair is thrown off, cartilage breakdown occurs. As a result of cartilage breakdown, damage to bone occurs. The result can be painful, tender, creaky joints and limitations on joint movement.

overweight, because obesity in women has definitely been shown to be a risk factor for development of knee osteoarthritis;

nutrition, because lack of vitamin D may predispose patients with established osteoarthritis of the knee to further progression.

What are the most common symptoms of osteoarthritis?Pain is the most common symptom, and it occurs primarily when the joint is moved, rarely at rest. Pain is often accompanied by crepitus (a crackling sound). Some patients experience a "gelling phenomenon" -- the perception of stiffness, usually lasting less than 20 minutes in the affected joint. Why some people have pain with osteoarthritis and others do not remains unknown. The perception of pain depends not only on the disease process and the brain's processing of main messages, but also on cultural, gender, and psychological factors. The joints most commonly involved are: the last and middle joint in the fingers; the joint that joins the thumb to the wrist; the hip; the knee; the neck; and the low back.

Osteoarthritis is not associated with the presence of fever, weight loss, anorexia, severe muscle atrophy, or symmetrical joint involvement. That is, when the left knee is affected, the right may not be -- in contrast to other forms of arthritis where both are apt to be affected, called symmetrical involvement. For more information, click here to read our full In-Depth Disease Overview on osteoarthritis.

What tests are done for osteoarthritis?Laboratory tests in osteoarthritis are important for the absence of any positive findings . Routine tests such as complete blood counts, urinalysis, sedimentation rate (ESR), biochemistries, and specialized tests such as rheumatoid factor and antinuclear antibody (ANA) are useful simply to exclude other diseases that cause joint pain. As we age, we sometimes develop a low level positive test for rheumatoid arthritis (rheumatoid factor) or ANA, and elevations of sedimentation rate (ESR) without obvious illness. These need not be confusing because, in arthritis, the clinical picture makes the diagnosis; lab tests tend only to confirm what your doctor already knows. The physician should never rely on laboratory tests as the sole indicator of disease when diagnosing arthritis. Other tests that may help confirm the diagnosis are: X-rays, aspiration of synovial fluid from the joint; and bone scans.

How is osteoarthritis treated?Treatment will depend on the severity of your osteoarthritis, any other diseases you have and what medications you are taking, all of which will be determined by the physician during a complete examination. Treatment is aimed at control of pain by decreasing inflammation in the joint and with analgesics; oral medications may be prescribed or injections into the joint. With the help of the physician and literature from the Arthritis Foundation, patients should first educate themselves about the disease and the various therapy modalities, such as physical and occupational therapy, especially the importance of exercise to strengthen your thigh muscles, which reduces pain and improves function in patients with osteoarthritis of the knee. It is also wise to maintain good nutrition and, if you are overweight, reduce.

Why should you consider surgery?When conservative measures for treating osteoarthritis fail and pain in a specific joint disables an active individual, then surgery may restore patient comfort and normal activity. Keep in mind that surgery relieves pain more than it restores range of motion. Thus, the decision to undergo surgery is one more of personal wishes than of medical priorities. The best candidate for surgery is the patient who has a definite interruption in some activity of daily living (i.e. can't walk more than a block or awakens from sleep with pain in the affected joint) and who has not been helped sufficiently by exercise and drug therapy. For such patients, the result will be outstanding because they will be pain-free in the involved joint. The type of surgery suggested will depend on your age, activity level, and the joint involved. When appropriate, total joint replacements are available for almost every joint in the body.